1. Technical Field
The present invention relates to a facsimile apparatus and method, and in particular, to a device and method for accurately detecting a document size.
2. Related Art
In general, facsimile machines employ scanners which can scan a document of one size or the other (for example, A4 size, B4 size or A3 size). Thus, when transmitting a B4-size document, a facsimile typically tracks to determine whether the called facsimile will be able to receive a B4-size document. If the called facsimile cannot receive such a size document, the sending facsimile scales down the image scanned in B4 size to an image in A4 size before transmitting the scanned image. Thus, in order to prevent unnecessary scanning and unnecessary downscaling, it is necessary for such a facsimile to first detect the document size prior to scanning the actual document area.
However,. when a plurality of documents of different sizes are inserted continuously into a facsimile apparatus, the facsimile cannot detect accurate sizes for each individual document. That is to say, if as an example, A4-size documents and B4-size documents are inserted continuously and in mixed fashion, the composition and operation of facsimile machine is such that the central processing unit (CPU) of the facsimile machine controls the scanner to scan the area corresponding to a B4-size document even though a A4-size document is in position for scanning. This is complicated by the fact that, if called facsimile cannot receive a B4-size document, the facsimile machine scales down the scanned image before transmitting it to the called facsimile.
Thus, there is a problem with such facsimile apparatus in that, in such situations, the CPU can misrecognize the A4-size document for a B4-size document, and scan an area corresponding to the B4-size document even though the document being scanned is of A4-size. Moreover, the scanner scans unnecessary area, and often unnecessarily scales down the scanned image before transmitting if the called facsimile cannot receive a certain size document.
Improved facsimile machines could be provided with additional scanners, and in particular with one scanner for each type or size of document to be scanned. However, this causes unnecessary increase in the cost of the facsimile.
Therefore, there is a need in the prior art for the development of a scanner which can scan a mixture of different size documents without misrecognizing the size of the documents, and which does not unnecessarily scale down images for called facsimiles which do not have the capability of receiving certain size documents. Furthermore, there is a need for the development of a facsimile machine which is not burdened by these disadvantages, but which also does not have an increased cost due to the provision of duplicate scanners for different size documents.
The following patents are considered to be representative of the prior art, and are burdened by the disadvantages set forth herein: U.S. Pat. No. 5,236,072 to Cargill, entitled Document Size Detection Device, U.S. Pat. No. 5,218,408 to Inada et al., entitled Image Forming Apparatus With Photosensors For Detecting Original Size, U.S. Pat. No. 5,500,725 to Takasu et al., entitled Original Document Reading Device Capable Of Automatically Detecting The Size Of An Original Document, U.S. Pat. No. 5,206,744 to Kamada et al., entitled Document Scanning Apparatus Having Image Signal Correcting Capability, U.S. Pat. No. 5,563,699 to Tsukamoto, entitled Document Feeder Which Determines A Document Path Using A Determined Page Length, U.S. Pat. No. 5,541,713 to Takatuski et al., entitled Device For Estimating A Size Of An Original Document, U.S. Pat. No. 5,602,651 to Tabata et al., entitled Image Recording Apparatus, U.S. Pat. No. 5,414,522 to Moriya, entitled Image Reading Apparatus Which Detects Document Size, U.S. Pat. No. 5,119,130 to Tsudaka et al., entitled Document Size Detecting Device, U.S. Pat. No. 5,198,853 to Ichihara et al., entitled Document Size Detection Apparatus, U.S. Pat. No. 5,568,281 to Kochis et al., entitled Automatic Document Presence,. Skew And Width Detection Method And Apparatus For A Document Scanner, and Japanese Patent No. 59-88757 to Tachikawa, entitled Electrophotographic Device.